Coil winding is a process used to produce an electromagnetic field by winding an electric conductor wire in the shape of a coil, spiral, or helix. The structure of the magnetic field, which includes its inductance, resistance, and strength, depends on the design and shape of the coil winding.
The electromagnetic field of a coil winding is created by passing an electric current through the wire of the coil. A varying magnetic field passes through the interior of the coil to generate a current in the conductor.
How the coil is wound determines its efficiency and conductivity. The differing winding processes are designed to serve a certain purpose for the creation of the electromagnetic field. The forms of coil winding are pancake, jumble or wild, toroidal, helical, and orthocyclic. In the winding process, wires should be tightly and densely packed to reduce air flow, or space, in order to increase the efficiency and reliability of the coil as well as the coils heat conductivity.
Jumble, or wild, winding has poor fill factors. Wires are placed randomly, causing a wider distribution of wire lengths and ranges of electric coil resistances. Though this is a disadvantage in coil winding, it is used in mass production because it can be done quickly without the need of operator oversight. Jumble windings are used as relay coils, for small transformers, ignition coils, and small electric motors using small wire gauges of 0.05 mm or less.
Orthocyclic winding has an optimal fill factor for round wires. The upper layers of wires are placed in the grooves of the lower layers. The greatest volume is achieved by winding the wires parallel to the coil flange. Winding goes around the coil body to meet the previous wire and make a step with the size of the wire gauge, which is called a winding step. The area of the step depends on the gauge of the wire and the coil bobbin geometry.
Toroid windings are used with low frequency electricity. A toroid is used as an inductor to boost the frequency. As the toroid turns, it increases the frequency. Toroids are produced by winding copper wire through a circular ring, which is evenly distributed over the circumference of the ring. The benefits of toroid windings are low core loss with power density.
Several types of windings are referred to as pancake because of the conductors being arranged as discs. The term actually refers to a type of coil that is in shell form transformers. In pancake windings, conductor wires are wound in a rectangular pattern with their wide face horizontal or vertical. It is a winding that is used for interleave arrangements.
Helical winding is cylindrical and leaves a gap between adjacent turns. The winding consists of flat parallel rectangular conductors that are close to each other in the radial direction of the winding. Uniform distribution of current between the parallel branches is created by transpositioning of the conductors.